Daren Matthews

Planning for Voice over IP requires an understanding of the various headers added when transporting packetised voice, espcially over an IPSec VPN: Read more…

A great alternative to SPAN and RSPAN, is to use the actual IOS itself as the packet sniffer! Capture traffic from the CLI and when you need to, export the data as a “.cap” (Wireshark, etc) file. to your PC. Read more…

Who invented Ethernet? Robert Metcalfe got the idea for the Ethernet protocol when he read a 1970 computer conference paper by Norman Abramson of the University of Hawaii about the packet radio system called ALOHAnet linking the Hawaiian Islands: Read more…

1P1Q3T – ingress queuing
As switch platforms have architectures based on oversubscription, they have been engineered to guarantee QoS by protecting critical traffic trying to access the backplane/stack-ring via ingress queuing. Read more…

The Cisco 2960, 2970, 3560 and 3750 Catalyst switches support a 1p3q3t que model which provides 3 thresholds in which to drop traffic. Read more…

Deciding upon a QoS Classification and Marking strategy can be a difficult task. Cisco have provided certain recommendations which may be implemented as a baseline QoS strategy and then altered over time: Read more…

The basic QoS Model

Actions at the ingress interface include classifying traffic, policing, and marking: Read more…

RFC 4594 describes some example and provides guidelines for DiffServ service classification which may be used as guidelines or as a basis for a QoS Classification Strategy: Read more…

The Modular QoS CLI (MQC) command structure found in Cisco IOS® Software requires a class map is built incorporating the ACLs that identify the traffic that will have QoS applied to them. Read more…

The first element to a QoS policy is to classify/identify the traffic that is to be treated differently.  Following classification, certain “marking tools” can set an attribute of a frame or packet to a specific value. Such marking (or remarking) establishes a trust boundary that scheduling tools later depend on. Read more…